This invention relates generally to sliders for adjustment of the suspension of a vehicle longitudinally with respect to the body of the vehicle and, more particularly, to apparatus for facilitating such adjustment.
This invention is especially concerned with sliders which enable adjustment of the suspension of a tandem axle trailer longitudinally relative to the van of the trailer. Conventional sliders used for this purpose typically comprise a pair of side rails secured at the left and right sides of the van in fixed position extending longitudinally of the van, and a frame which carries the suspension comprising left and right slide members slidable longitudinally of the van on the side rails. A plurality of locking pins lock the frame in various positions of adjustment relative to the side rails, the locking pins being retractible for permitting adjustment of the frame to a selected position of adjustment and extensible for locking the frame in the selected position of adjustment. The locking pins are connected for conjoint movement between extended and retracted positions by linkage, and the pins are normally urged to their extended position by a plurality of springs. The linkage is operable to retract the pins by a pull rod extending laterally outwardly at one side of the slider frame.
While the pull rod design described above has been used for years, it has a serious drawback. This is due to the fact that the locking pins often become stuck in extended position (due to the pins becoming wedged in openings in the slider frame, for example), thus making it difficult if not impossible to operate the pull rod to retract the pins. In this event, the operator of the vehicle typically tries to jog the trailer (drive it forward and/or rearward in short spurts) until the pins are sufficiently freed to enable the pull rod to be operated. This is inconvenient and time consuming, especially if there is only one person operating the vehicle, since there is no indication while jogging the trailer as to when the pins are in fact free. Thus, after jogging the trailer the operator may find that the pins are still stuck, necessitating that the entire procedure be repeated. One solution to this problem is to have a second person pull on the pull rod while the trailer is being jogged, so that the pins will retract as soon as they become free. However, a second person is not always available. And even if a second person is available, grasping and pulling the handle while the vehicle is moving poses a risk of injury.